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G ROUNDING AND P ROTECTION OF TUNNEL FEEDERS , ANTENNAS AND RADIATING CABLE FOR ELECTRIC

In document Network Design Grounding principles (sider 17-22)

4.6.1 1 x RF-Repeater and tunnel antenna

1/2"

RFR

1/2" S

1/2" S 15 KV

Figure 11 RF-Repeater and Tunnel Antenna.

• The antenna is isolated from the tunnel rock to avoid return current from the train to flow trough the antenna.

• The DC-block (inside the tube or cable trace) isolates the rail ground from the ground in the equipment shelter, and prevent all DC currents from flowing through the cables.

4.6.2 1 x RF-Repeater and radiating cable with 50 ohm termination

15 kV

RC 1 1/4"

1/2"

RFR

1/2" S

1/2" S

Figure 12 RF-Repeater, RC and 50 Ohm termination.

• The DC-block isolates the rail ground from the ground in the equipment shelter, and prevent all DC currents from flowing through the cables.

4.6.3 1 x RF-Repeater and radiating cable with antenna inside the tunnel

1/2"

RC 1 1/4"

1/2"

RFR

1/2" S

1/2" S

15 kV

Tunnel Antenna/

Overlap Antenna 15 kV

Figure 13 RF-Repeater, RC and overlap antenna inside the tunnel.

• The antenna is isolated from the tunnel rock to avoid return current from the train to flow trough the antenna.

• The DC-blocks isolates the rail ground from the ground in the equipment shelter, and prevent all DC currents from flowing through the cables.

4.6.4 1 x RF-Repeater and radiating cable with antenna outside the tunnel

1/2" RC 1 1/4"

1/2"

1/2"

Overlap Antenna

RFR

1/2" S

1/2" S

15 kV 15 kV

• The DC-blocks isolates the rail ground from the ground in the equipment shelter, and prevent all DC currents from flowing through the cables.

• A surge arrestor is connected close to the antenna to protect the radiating cable and the repeater equipment against lightening. The surge arrestor is connected to the ground cable coming from the antenna. Local ground is established. It is not necessary to isolate the antenna from the rock.

4.6.5 2 x RF-Repeater and radiating cable

1/2" RC 1 1/4"

RFR

1/2" S

1/2" S

1/2"

RFR

1/2" S

1/2" S

15 kV 15 kV

Figure 14 2 RF-Repeaters and RC

• The DC-blocks isolates the rail ground from the ground in the equipment shelter, and prevent all DC currents from flowing through the cables.

4.6.6 Overlap/HO-antenna on the repeater side

RFR

1/2" S

1/2" S

16dB Main

1/2" S

1/2" S

Overlap Antenna

1/2"S

To tunnel 15 kV

Figure 15 RF-Repeater and Overlap Antenna on the repeater side.

• It is not necessary to isolate the antenna from the rock because it will be connected to the local ground

• The DC-blocks isolates the rail ground from the ground in the equipment shelter, and prevent all DC currents from flowing through the cables.

If the antenna and feeders are not closer than 5m from the tracks, the same solution as for non-electrical lines shall be used.

4.6.7 1 x Remote Unit and antennas

Figure 16 Remote Unit and Antennas

• The antennas are isolated from the tunnel rock to avoid return current from the train to flow trough the antenna.

• The DC-blocks prevent all DC currents from flowing through the cables.

4.6.8 1 x Remote Unit and radiating cable

1/2" S

Figure 17 Remote Unit and Radiating Cable.

• The DC-blocks isolates the rail ground from the ground in the equipment shelter, and prevent all DC currents from flowing through the cables.

Note: There shall not be more than one earth kit on the radiating cable. That is only one earth kit between two DC-blocks.

4.6.9 Combinations of Remote Unit and RF-Repeater with radiating cable or 2 x Remote Unit with radiating cable

4.6.9.1 RF-Repeater and Remote Unit with radiating cable For the RF-Repeater use the same principle as described for

2 x RF-Repeater and radiating cable.

For the Remote Unit use the same principle as described for 1 x Remote Unit and radiating cable.

4.6.9.2 2 x Remote Unit with radiating cable For each Remote Unit use the same principle as described for 1 x Remote Unit and radiating cable.

5 Grounding requirements for different roll-out site types

Netel has covered all aspects of main grounding for all various types of sites in the GSM-R project with respective grounding documents [3] - [29].

The main grounding is based upon a ring structure around the cabin/tower etc. All equipment (both 230V AC and 48V DC) will be connected to this ring on separate places. The ring will be extended with branches and terminated in the ground with x1 nos. spears. The overall goal is to achieve a resistance of 40Ω. This is again dependant upon type of soil (swamp, rock, water or normal soil). All 48V DC telecom equipment will be grounded in the cabin on its own ground bar in one of the service racks, and from thereon be connected to the ring at a suitable place.

The grounding, for all different types of sites, will differ only when the site2 is within the “slyngfelt” of electric railway lines. This is further described in chapter 4 Grounding principles tunnel system. The major differences are described below:

Non-electrical lines

• Antennas and radiating cables inside tunnels will not be grounded unless there is a risk of lightning.

• The antenna must be isolated from the rock to avoid different ground potential between the antenna and the repeater equipment if the antenna doesn’t have local ground

Electrical lines

• Every antenna and radiating cable will be grounded.

• The antennas should always be isolated from the tunnel rock to avoid return current from the train to flow trough the antenna.

• The repeater equipment grounding shall be isolated form other ground potentials.

• The grounding in the shelter must not be connected directly to the rail ground.

1 x – Number of spears depend upon the type of ground conditions, i.e. water, swamp, rock or normal soil.

2 There are currently no BTS/MW sites planned within the ”slyngfelt” of electrical lines.

Reference List

# Doc. no. Document name Comment

[1] Jernbaneverket's tekniske regelverk, "Regler for prosjektering og bygging".

JD 560 chapter 9,

[2] Jernbaneverket's tekniske regelverk, "Regler for prosjektering og bygging".

JD 510 chapter 6, section 2.1

[3] GSM-00-X-10200 Detaljer jording Jording – generelt

[4] GSM-00-X-10201 Kategori 1 – under 30 Ohm.

Jording i fjellgrunn

Jording – generelt [5] GSM-00-X-10202 Kategori 1 – under 30 Ohm.

Jording i fjell og jord

Jording – generelt [6] GSM-00-X-10203 Kategori 1 – under 30 Ohm.

Jording i jord

Jording – generelt [7] GSM-00-X-10204 Kategori 2 – under 60 Ohm.

Jording i fjellgrunne

Jording – generelt [8] GSM-00-X-10205 Kategori 2 – under 60 Ohm.

Jording i fjell og jord

Jording – generelt [9] GSM-00-X-10206 Kategori 2 – under 60 Ohm.

Jording i jord

Jording – generelt [10] GSM-00-X-10207 Kategori 3 – under 100 Ohm.

Jording i fjellgrunne

Jording – generelt [11] GSM-00-X-10208 Kategori 3 – under 100 Ohm.

Jording i fjell og jord

Jording – generelt [12] GSM-00-X-10209 Kategori 3 – under 100 Ohm.

Jording i jord

Jording – generelt [12] GSM-00-K-15020 Jording radiohytte Ringjord m/stråler i løsmasser Jording – generelt [13] GSM-00-K-15021 Jording radiohytte Ringjord m/jordspyd i løsmasser Jording – generelt [14] GSM-00-K-15022 Jording radiohytte Ringjord m/kråkefot i myr Jording – generelt [15] GSM-00-K-15023 Jording radiohytte Ringjord m/jordspyd i fjell Jording – generelt [16] GSM-00-K-15024 Jording radiohytte Jordingsanlegg m/jordspyd i fjell Jording – generelt [17] GSM-00-K-15025 Jording radiohytte i Ringjord m/plate i vann Jording – generelt [18] GSM-00-K-15026 Jording radiohytte Ringjord m/jordspyd i fjell 2m Jording – generelt [19] GSM-00-K-15027 Feste av jordledning Klammer på fjell Jording – generelt [20] GSM-00-K-15029 Jordingsdetalj krav til bøyeradius Jording – generelt

[21] GSM-00-K-15030 Jording Jordspyd i fjell Jording – generelt

[22] GSM-00-K-15031 Feste av jordeledning Klammer for PN 50mm2 Jording – generelt [23] GSM-00-K-15034 Jording repeater ramme Jordspyd i tunnel Jording – generelt

[24] GSM-00-K-15035 Jordspyd i fjell 2m hull Jording – generelt

[25] GSM-00-K-15082 Jording i grus mast i grus Jording – generelt [26] GSM-00-K-15075 Jording impedans til skinner kabelføring feste til skinne Jording – spesielt

elektrifisert bane [27] GSM-00-K-15109 Prinsipper for jording av RC, antenner og repeater skisse

1-3

Jording – spesielt elektrifisert bane [28] GSM-00-K-15113 Prinsipper for jording av RC, antenner og repeater skisse

4-6

Jording – spesielt elektrifisert bane [29] GSM-00-K-15114 Prinsipper for jording av RC, antenner og repeater skisse

7-9

Jording – spesielt elektrifisert bane

In document Network Design Grounding principles (sider 17-22)